Compilare: main.cpp: In member function 'void trie::add_string(std::__cxx11::string&)': main.cpp:63:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<to_add.length(); i++) ~^~~~~~~~~~~~~~~~ main.cpp: In member function 'void trie::erase_string(std::__cxx11::string&)': main.cpp:81:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<to_delete.length(); i++) ~^~~~~~~~~~~~~~~~~~~ main.cpp: In member function 'node* trie::get_root(std::__cxx11::string&)': main.cpp:101:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<prefix.length(); i++) ~^~~~~~~~~~~~~~~~ main.cpp: In member function 'int trie::get_longest_common_prefix_of_string(std::__cxx11::string&)': main.cpp:118:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<prefix.length(); i++) ~^~~~~~~~~~~~~~~~ main.cpp:117:13: warning: unused variable 'maxx' [-Wunused-variable] int maxx=0; ^~~~ main.cpp: In function 'int main()': main.cpp:142:9: warning: unused variable 'a' [-Wunused-variable] int a,b; ^ main.cpp:142:11: warning: unused variable 'b' [-Wunused-variable] int a,b; ^